Chaeles cocheane



UN ED STA E PATENT OFFICE,

CHARLES oocn'nANn, or srounnninen, COUNTY or wononsrnn, ENGLAND.

MANUFACTURE IRON IN BLAST-FURNACES.

' SPECIFICATION formingpart of Letters Patent no. 284,383, dated September 4, 1883. Application filed Deeemberiil), 1882. (No-specimens.) Patented in England October 19, 1882, No. 4,9?6.

T (dl whom it may concern:

Be it known that 1, CHARLES Oocnnilnn, a citizen of England, residing at Stourbridge, in the county of YVorcester, England, have invented a new and useful Improvement in the llIanufacture of Iron in Blast-Furnaces, (for which I have obtained a patent in Great Britain, No. 4,986, dated October 1.9, 1882,) of which the following is a specification.

It has been found that the principal cause of the loss of fuel in blast-furnaces of ordinary construction is due to the carbonic acid evolved both from the limestone and from the ore in ,being reduced at the red-hot zone of the furnace,.which carbonic acid takes up carbon from the incandescent fuel to form carbonicoxide gas,whieh passes away. Now, according to my present invention, I more or less prevent the production of carbonic acid from the above substances at the red-hot zone, first, by constructing the furnace of such a large size relatively to the size of the lumps of oretreated that the reduction of the ore shall be practically completed before it reaches the red hot zone; and, secondly, I employ, in

combination with such construction of furresulting caustic lime should be drawi'i froin' the kiln while still warm, and be protected from exposure to'rain or weatherby being loaded into barrowsor trucks suitably in closed, and by preference arranged so that they will open of themselves when the barrow is to be ei'nptled. By this means the caustic lime will be prevented fron'r absorbing any sensible proportion of carbonic acid or water from the ati'nosphere. ,In furtheraiiice of this protection, the caustic lime shoul.d be charged in its suitable proportion for smelting pur poses directly onto the charging-bell of the blast-furnace, or into the furnace itself, and as quickly as possible be covered up either with coke or iron-stone.

By this means, when the charge is lowered into the furnace, as thelime is below theother materials of the charge, it will not be liable to absorb the aqueous vapor rising from themoist coke or moist iron-stone,

i which it would do if placed abovethese; also,

the interval of time between the introduction of the consecutive charges will be utilized in enabling the moisture contained in the coke and iron-stone of the previous charge (which may be considerable, especiallyinthe coke, in wet weather) to be driven off before the fresh charge of lime falls onto them, The object of the above precautionsis to prevent, as far as possible, the formation of hydrate of lime, commonly known as slaked lime, which would be as detrimental to the economic Working of the furnace, if not more so, than the limestone with its contained carbonic acid.

As before stated, inorderto effect the suc cessful working of blast-furnaces according to my invention, it is also necessary that thesize of, the blast-furnace shall be so proportioned relatively to the size of the lumps of iron stone charged that the whole of this shall become reduced orconverted into sponge of iron before it reaches the red-hot zone. If this precaution be not taken-that is to say, if the lumps of ore are-of such a size that they will descend through the upper part of the furnace and reach the red-hot zone before the whole of their mass could be properly acted upon by the carbonic oxidecarboni c acid will be evolved from the process of reduction in the presence of the red-hot coke, and this will be partly taken up by the caustic lime, which will thus become reconverted into carbonate of lime, to beagain reduced in a still lower re gion, entailing a corresponding absorption of fuel in the process. Thus, toavoid this occurrence, if large lumps of iron-stone,or even a mixture of large and small lumps, be used, the furnace should be of very largedimensions; andI have found,'for instance, that a heigl'lt of about thirty feet above the red-hot zone is advisable for this purpose when lumps upon the size of the iron-stonelumps, but

also upon the nature of the ore, which may in some varieties be acted upon more readily by the carbonic oxide than in others.

I In all cases it is important to insure the IOO greatest possible dryness of both iron-stone and coke to obtain the fullest possiblebenefit from my above-described invention.

With regardto the quantity of causticlime to be used, it maybe stated that, assuming the limestone to be pure and perfectly calcined, then in place of fivehundred-weight of limestone,now used per ton of pig-iron made, only 2.8 hundred-weight of caustic lime need be used; and, in the same proportion, in place of tenhundred-weight of limestone only 5.6 hundred-weight of limestone, 8.4 hundred-weight of lime, and so on. These proportions main the same, no matter what size furnace is used, so long as the ore is reduced therein before reaching the red-hot zone.

Having thus described the nature of my in vention and in What manner the same is to be performed, I wish it to be understood that I do not claim, generally, the use of caustic lime in blast-furnaces, as I am well aware that this has been already tried, but under condi;

tions and for purposes different from those of my before-described invention; but

I clain1 The within-described method of working blast-furnaces, consisting in charging the furnace with ore in the presence of caustic lime, the furnaceand ore being'of relative dimensions to each other, as set forth, whereby. the complete reduction of ore before it reaches the red-hot zone is effected and the amount of carbonic-acid gas evolved at the zone diminished.

In testimony whereof I have signed my name 3 5 to this specification, in the presence of two subscribing witnesses, this 11th day of December, A. D. 1882.

, CHARLES COOHRANE. Vitnesses:

WILLIAM J oNADAB TURNEY, JOHN PALMER HALL.

Correction in Letters Patent No. 284,383.

It is hereby certified that in Letters Patent, No. 284,383, granted September 4, 1883, upon the application of Charles Cochra-ne, of SLourbridge, county of Worcester, Euglaud, fer an improvement in the Manufacture of Iron in Blast-Furnaces, an error appears requirihg the following correction, viz: in line 12, page my the pririted specifica-tion, the words, mm,- in place of 15 hundred weight, should u msmfa'fmr the 'word weight and before the words of limestone; and the-t; the patent should be read with this correc tiou therein to make it. conform to the record of the casein the Patent, Office.

Signed, eouutersignul, and sealed this 13th day 0|" November, A. D. I883.

M. L. JOSLYN, Acting Secretary of the Interior.

[SEAL] Countersigned BENJ. BUTTERWORTII,

Commissioner of Patents. 

